She has no children, so that would be a short dynasty!
Besides Mrs. Angela Merkel is the head of the government, the equivalent of David Carmeron. She is not the head of the state, like the queen. And she'd probably never be able to keep her hands out of politics, as it is expected of a good Queen in the 21st century.

That's a nice idea. I liked Richard von Weizsäcker a lot. He was a great man and as a “Freiherr“ he was even a member of the former german nobility. King Richard of Germany has a nice ring to it. And it would have been a continueing dynasty unlike the Merkel-Dynasty, because “King Richard“ has four children. Three sons (although one died already) and one daughter.

Unfortunatly this is all daydreaming, because Germany will never be a monarchy again for all the previously mentioned reasons. But one can still dream.